The paper-feeding mechanism is a key part of the sheet-fed lithographic printing machine. If improper adjustment occurs, the paper-feeding movement will be unstable, paper-cutting errors, line speeds will be different, and the overprinting will be inaccurate. Therefore, it is very important to accurately adjust the delivery mechanism.
The paper-feeding mechanism of a sheet-fed offset press is generally an eccentric rotary paper-feeding mechanism. The swinging cam moves the paper-transmitting tooth through a four-bar linkage mechanism. At the same time, the paper feed shaft is installed in an eccentric sleeve with an eccentricity of 20 mm, and the gear is rotated at a uniform speed. Therefore, the motion of the transfer tooth itself is a uniform rotational motion of the swing center around the eccentric center. Its trajectory is a "water drop" shaped closed curve. Due to the use of rotational eccentricity, the center of swing of the paper-feeding teeth at the time of the return stroke is improved, so that the stability and the transmission accuracy of the paper-feeding teeth can be improved. However, due to the increase of the eccentric rotational motion, the transfer tooth movement is complicated and the adjustment difficulty is also increased.
In order to improve the accuracy of the transfer and transfer of paper, there must be stringent requirements for the movement of the various stages of the machine, especially the movement of the junctions.
In order to improve the stability of the paper-feeding teeth and the accuracy of the paper-feeding, the paper-feeding teeth are required to be at a standstill when closing the papers due to errors in cam machining, abrasion, and vibration. Therefore, the roller and the swing cam should be at a relatively stationary state when the paper feed teeth are gripping. The specific adjustment method is that when the roller runs to the lowest position of the swing cam, the back screw is adjusted so that the gap between the roller and the swing cam is 0.03 mm-0.05 mm, so that the time for the paper teeth to stop on the back is the corresponding corner of the impression roller. °.
Due to the high speed operation of the machine, vibration may occur, and the paper feeding tooth is unstable when it stops on the backing. Vibration is required to purchase paper. In addition, the front rule must wait for paper to pass through the paper before it can be transferred to the impression cylinder. A brief process is also required here. Therefore, the specific movement time of the paper-making mechanism should be reasonably distributed: the paper-feeding tooth should be stopped on the backing, and then the impression cylinder should be turned over 17° and the paper-feeding teeth should be raised after closing the teeth. , Then the 5° delivery paper starts to transfer paper to the impression cylinder.
When the swing center of the paper-feeding tooth is at the moment of vertically handing the paper table on the line connecting the center of the eccentricity and the middle point of the paper-transmitting mouth, the vertical upward speed of the mouth is 0. At this time, the crepe paper is in the momentary rest state, which is the most Good moments. During the adjustment, under the premise of a zero position of the whole machine, the machine is operated to the position of the mouth of the speed paper mouth. When the position of the paper conveying tooth pad is the lowest from the delivery tooth, the roller controlling the closed feeding tooth is disengaged and installed on the transmission side. The rotating tooth on the paper feed shaft opens and closes the tooth cam. Under the action of the spring force, the paper feed tooth chip just closes in this motion position, and the paper picking accuracy is best. If the pad is not at the lowest position when picking up the paper, the work surface of the pad is not parallel to the transfer table. In this way, when closing the teeth, the pick-up pad will pick up the opening of the paper slightly and close it. The front of the paper is bent so that it will cause a paper creping error.
Since the transfer teeth are used for variable speed motion, the speed is accelerated from zero to the surface speed of the impression cylinder, and the impression cylinder is performing a uniform rotational motion. Therefore, the angle at which the paper teeth pass by during the transfer phase and the impression cylinder are The angle turned is not the same, so when the delivery tooth reaches the delivery point, the axis of the delivery tooth—the center of swing has exceeded the center line of the transfer gear and the impression cylinder, that is, the delivery tooth When the paper is sent to the transfer point, the angle between the swing center and the center line of the eccentric teeth of the paper-transmitting teeth and the center line of the eccentric sleeve and the impression cylinder is 18°. This is the adjustment of the transfer of the transfer paper to the impression cylinder. The main basis. The line speed of the transfer paper before transfer is greater than the line speed on the surface of the impression cylinder, and its maximum value exceeds the line speed on the surface of the impression cylinder by 10%, and then it drops to the constant transfer speed.
When the paper handing teeth and the impression cylinder are handed over, in order to ensure that the papers are handed over accurately, the overprinting accuracy is ensured at the point of intersection, and the speed of the paper handing teeth and the impression cylinder should be the same and the directions are opposite. In addition, in the transfer process, the paper can not be empty, transfer paper teeth and the impression cylinder teeth together hold the paper synchronous operation 2-3mm, delivery paper tine escaping from the edge of the imprinting roller advance 0.5-1mm, delivery paper teeth The lowest position of the pad is 0.3mm from the surface of the impression cylinder and 0.3mm from the surface of the transfer tooth.
In addition, the transfer paper should be no less than 8mm, and the pressure of the paper must be the same, and the level of the dental pad must be the same. In this way, accurate overprinting can be ensured
The paper-feeding mechanism of a sheet-fed offset press is generally an eccentric rotary paper-feeding mechanism. The swinging cam moves the paper-transmitting tooth through a four-bar linkage mechanism. At the same time, the paper feed shaft is installed in an eccentric sleeve with an eccentricity of 20 mm, and the gear is rotated at a uniform speed. Therefore, the motion of the transfer tooth itself is a uniform rotational motion of the swing center around the eccentric center. Its trajectory is a "water drop" shaped closed curve. Due to the use of rotational eccentricity, the center of swing of the paper-feeding teeth at the time of the return stroke is improved, so that the stability and the transmission accuracy of the paper-feeding teeth can be improved. However, due to the increase of the eccentric rotational motion, the transfer tooth movement is complicated and the adjustment difficulty is also increased.
In order to improve the accuracy of the transfer and transfer of paper, there must be stringent requirements for the movement of the various stages of the machine, especially the movement of the junctions.
In order to improve the stability of the paper-feeding teeth and the accuracy of the paper-feeding, the paper-feeding teeth are required to be at a standstill when closing the papers due to errors in cam machining, abrasion, and vibration. Therefore, the roller and the swing cam should be at a relatively stationary state when the paper feed teeth are gripping. The specific adjustment method is that when the roller runs to the lowest position of the swing cam, the back screw is adjusted so that the gap between the roller and the swing cam is 0.03 mm-0.05 mm, so that the time for the paper teeth to stop on the back is the corresponding corner of the impression roller. °.
Due to the high speed operation of the machine, vibration may occur, and the paper feeding tooth is unstable when it stops on the backing. Vibration is required to purchase paper. In addition, the front rule must wait for paper to pass through the paper before it can be transferred to the impression cylinder. A brief process is also required here. Therefore, the specific movement time of the paper-making mechanism should be reasonably distributed: the paper-feeding tooth should be stopped on the backing, and then the impression cylinder should be turned over 17° and the paper-feeding teeth should be raised after closing the teeth. , Then the 5° delivery paper starts to transfer paper to the impression cylinder.
When the swing center of the paper-feeding tooth is at the moment of vertically handing the paper table on the line connecting the center of the eccentricity and the middle point of the paper-transmitting mouth, the vertical upward speed of the mouth is 0. At this time, the crepe paper is in the momentary rest state, which is the most Good moments. During the adjustment, under the premise of a zero position of the whole machine, the machine is operated to the position of the mouth of the speed paper mouth. When the position of the paper conveying tooth pad is the lowest from the delivery tooth, the roller controlling the closed feeding tooth is disengaged and installed on the transmission side. The rotating tooth on the paper feed shaft opens and closes the tooth cam. Under the action of the spring force, the paper feed tooth chip just closes in this motion position, and the paper picking accuracy is best. If the pad is not at the lowest position when picking up the paper, the work surface of the pad is not parallel to the transfer table. In this way, when closing the teeth, the pick-up pad will pick up the opening of the paper slightly and close it. The front of the paper is bent so that it will cause a paper creping error.
Since the transfer teeth are used for variable speed motion, the speed is accelerated from zero to the surface speed of the impression cylinder, and the impression cylinder is performing a uniform rotational motion. Therefore, the angle at which the paper teeth pass by during the transfer phase and the impression cylinder are The angle turned is not the same, so when the delivery tooth reaches the delivery point, the axis of the delivery tooth—the center of swing has exceeded the center line of the transfer gear and the impression cylinder, that is, the delivery tooth When the paper is sent to the transfer point, the angle between the swing center and the center line of the eccentric teeth of the paper-transmitting teeth and the center line of the eccentric sleeve and the impression cylinder is 18°. This is the adjustment of the transfer of the transfer paper to the impression cylinder. The main basis. The line speed of the transfer paper before transfer is greater than the line speed on the surface of the impression cylinder, and its maximum value exceeds the line speed on the surface of the impression cylinder by 10%, and then it drops to the constant transfer speed.
When the paper handing teeth and the impression cylinder are handed over, in order to ensure that the papers are handed over accurately, the overprinting accuracy is ensured at the point of intersection, and the speed of the paper handing teeth and the impression cylinder should be the same and the directions are opposite. In addition, in the transfer process, the paper can not be empty, transfer paper teeth and the impression cylinder teeth together hold the paper synchronous operation 2-3mm, delivery paper tine escaping from the edge of the imprinting roller advance 0.5-1mm, delivery paper teeth The lowest position of the pad is 0.3mm from the surface of the impression cylinder and 0.3mm from the surface of the transfer tooth.
In addition, the transfer paper should be no less than 8mm, and the pressure of the paper must be the same, and the level of the dental pad must be the same. In this way, accurate overprinting can be ensured
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